1. Field of the Invention
The present invention relates to an antenna apparatus that acquires information from a body-insertable apparatus that is inserted into a subject and moves inside the subject, an antenna, an antenna holder that holds the antenna, and a body-insertable apparatus system.
2. Description of the Related Art
In the related art, endoscopes have been widely used as a medical observation apparatus that is inserted into a subject to observe the inside of a body cavity. Moreover, in recent years, a swallowable endoscope (capsule endoscope) in which an imaging device and a communication device that wirelessly transmits image data captured by the imaging device are included in a capsule-shaped casing has been developed. The capsule endoscope has a function of moving inside an organ such as, for example, the esophagus, the stomach, or the small intestine according to a peristaltic motion of the organ until the capsule endoscope is naturally egested from the subject after being swallowed from the mouth of the subject in order to observe the inside of the body cavity.
The image data captured inside the body cavity by the capsule endoscope while moving inside the body cavity is sequentially transmitted to the outside of the body via wireless communication and is stored in a memory provided inside or outside a receiving device that is outside the body, or is displayed on a display provided in the receiving device as an image. A doctor or a nurse can import the image data stored in the memory to an information processing device via a cradle to which the receiving device is inserted and perform a diagnosis based on the image displayed on the display of the information processing device or the image that is received by the receiving device and displayed on the display.
When a wireless signal is received from a capsule endoscope, in general, in a receiving device, plural receiving antennas are distributed outside a subject, one receiving antenna having the strongest received strength is selected, and a wireless signal is received by the selected receiving antenna. As an example of such a receiving device, a receiving device that switches plural receiving antennas disposed outside a subject and estimates the position of a capsule endoscope which is a transmission source of a wireless signal based on the received field strengths of the respective receiving antennas is known. Specifically, a configuration in which plural compact antennas are attached to the belly of a subject and a moving state of a capsule endoscope is detected using a difference in the received strengths of the wireless signals of the respective antennas is proposed (for example, see Japanese Patent Application Laid-open No. 2006-26163). Moreover, a configuration in which plural antennas are fixed to a belt-shaped member and is wound around the belly of a subject so as to easily attach the plural antennas to the subject is also proposed (for example, see Japanese Patent Application Laid-open No. 2006-271987).